Q.What is heterospory? Briefly comment on its significance. Give two examples.

Heterospory is the condition in which a plant produces two different kinds of spores instead of just one.

• The two kinds are large megaspores and small microspores.
• The megaspores germinate into female gametophytes, while the microspores germinate into male gametophytes.
• A plant that makes only one kind of spore is homosporous; one that makes two kinds is heterosporous. …

Most pteridophytes produce only a single type of spore, and such plants are described as homosporous. A few, however, break from this pattern and produce two different kinds of spores. This condition is called heterospory. The two spore types differ in size: the larger ones are the megaspores and the smaller ones are the microspores. They are not just different in size but also in what they become — the megaspores germinate to give female gametophytes, while the microspores germinate to give male gametophytes.

Why this matters becomes clear when we look at what happens next in a heterosporous plant. The female gametophytes are not shed and left to fend for themselves. Instead they are held on the parent sporophyte for varying lengths of time. While still attached and protected there, the zygote develops into a young embryo inside the female gametophyte. …